文档介绍：DATABASE SYSTEM CONCEPTS
instructor: Jingsheng Lei(雷景生)
E-mail: ******@hainu.
Chapter 1: Introduction
Applications of Database Systems
Database Systems versus File Systems
View of Data
Data Models
Database Language
Database Users and Administrator
Transaction Management
Database System Structure
Application Architectures
History of Database Systems
Summary
Database Management System (DBMS)
Collection of interrelated data.
Set of programs to access the data.
DB contains information about a particular enterprise.
DBMS provides an environment that is both convenient and efficient to use.
Database systems are designed to manage large bodies of information.
DBS must ensure the safety of the information stored.
Several users.
Data Database(DB) Database Management System
(DBMS) Database System(DBS)
1 Applications of Database Systems
Database Applications:
Banking: all transactions
Airlines: reservations, schedules
Universities: registration, grades
Sales: customers, products, purchases
Manufacturing: production, inventory, orders, supply chain
Human resources: employee records, salaries, tax deductions
Databases touch all aspects of our lives
2 Database Systems versus File Systems
In the early days, database applications were built on top of
file systems
Drawbacks of using file systems to store data:
Data redundancy and inconsistency
Multiple file formats, duplication of information in different files
Difficulty in accessing data
Need to write a new program to carry out each new task
Data isolation — multiple files and formats
Integrity problems
Integrity constraints (. account balance > 0) e part of program code
Hard to add new constraints or change existing ones
2 Database Systems versus File Systems(Cont.)
Drawbacks of using file systems (cont.)
Atomicity of updates
Failures may leave database in an inconsistent state with partial updates carried out
. transfer of funds from one account to another should plete or not happen at all
Concurrent a